If there is any odd number less than any even number the result should be false. 1 is odd and 2 is even. 1<2.

I completed the kata myself but this solution is greek to me. Guess I have a lot to learn

The tests for the Javascript version do not take into account the case where a users completes an activity 2 ranks or more below their own rank, even though this logic is stated as a requirement in the description,

The tests apply several ranks to your class in order, so the end result of the progress will not always be only the progress gained from that rank application.

In this example it seems you had a User object in the state where the rank was -7 and the progress was 70. So that when a rank of -4 was applied you are intended to gain 90 progress, rank up to rank -6 and have 60 progress remaining.